filterSimplify node

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This node implements a curve simplification filter, combining nearly colinear sets of input points into line segments, and is used by the applyTake command to process recorded motion capture data. The attributes of the node are settings which affect the operation of the filter as it is invoked by applyTake. These settings are preserved when the scene file is saved.

Curve simplification is achieved by copying to the filter output only those data value records which are the the endpoints of ranges of nearly colinear values within the input data. The colinearity test requires that all deleted data points lie within a parallelegram connecting the end-points with width 2 * tolerance * (max - min), where max and min are the extrema of the input data.

Points within these parrallelograms are considered colinear and not copied to the output data values subject to the following additional constraints.

Data records with time stamps closer than timeTolerance to the last output value time stamp are considered duplicate and skipped.

Ranges of input values combined into linear segements can be no shorter that minTimeStep and no longer that maxTimeStep in duration.

If subsequent data records contain identical values, only the first record is treated as valid data, unless allowDuplicates is set.

Notes

Since the base class inputs (comprising the input and output data and timestamp values) to this node are unconnectable, this node cannot be used in a traditional dependency graph sense.

Node name	Parents	MFn type	Compatible function sets
filterSimplify	filter	kFilterSimplify	kBase kNamedObject kDependencyNode kFilter kFilterSimplify

Attributes (5)

allowDuplicates, maxTimeStep, minTimeStep, timeTolerance, tolerance

Long name (short name) Type Default Flags

allowDuplicates (ad) bool true

If true, treat ranges of duplicate values as valid data, else ignore duplicate values as a device oversampling artifact.

maxTimeStep (mxt) double 3600

Max time step in seconds between output records.

minTimeStep (mnt) double 0.0

Minimum time step in seconds between output records.

timeTolerance (tt) double 0.00

Temporal tolerance for timestamps, in seconds. Data records closer than this value are considered duplicate and skipped.

tolerance (tol) double 0.001

The fraction of dynamic range of input which defines the limits of nearly linear.